CBSE Class 7 Science Our Environment Chapter 3 Our Changing Earth Important Questions - Free PDF Download
FAQs on Important Questions for CBSE Class 7 Science Our Environment Chapter 3 - Our Changing Earth
1. Explain the work of a river according to Chapter 3 - Our Changing Earth of Class 7 Social Science Our Environment.
The river's flowing water erodes the landscape. A waterfall is formed when a river flows at a steep angle over exceptionally hard rocks or down a deep valley side. The river twists and turns as it enters the plains, forming huge bends known as meanders. The ends of the meander loop are getting closer and closer due to constant erosion and deposition along the meander's sides. The meander loop eventually separates from the river and forms a cut-off lake, also known as an ox-bow lake. The river occasionally breaches its banks, producing flooding in the surrounding areas. It deposits sediments along its banks as it floods, which are layers of fine dirt and other debris.
2. Give an account of the work of wind according to Chapter 3 - Our Changing Earth of Class 7 Social Science Our Environment.
In deserts, the wind is a major cause of erosion and deposition. Mushroom rocks are rocks that have the shape of a mushroom and are commonly found in deserts. The lower section of the rock is eroded more by the wind than the higher section. As a result, such rocks have a smaller base and a larger top. The wind lifts and moves sand from one location to another when it blows. Sand falls and is deposited in low hill-like structures when the wind stops blowing. Dunes are what they're called. When grains are very fine and light, they can be carried over long distances by the wind. Loess is the name given to sand that has been deposited over a broad area.
3. Give an account of earthquake preparedness according to Chapter 3 - Our Changing Earth of Class 7 Social Science Our Environment.
An earthquake is a natural disaster that we cannot prevent. However, if we are prepared ahead of time, we can lessen the impact. We should move to a safe location in the event of an earthquake. We should hide behind a kitchen counter, table, or desk against a door or a wall on the inside. We should avoid fireplaces, locations around chimneys, and windows with reflective surfaces, such as mirrors and picture frames. Furthermore, we should make our friends and family members aware of the situation.
4. Mention the work of ice according to Chapter 3 - Our Changing Earth of Class 7 Social Science Our Environment.
Glaciers are glacial rivers that erode the environment by removing soil and stones, exposing solid rock beneath. Deep gorges are carved out by glaciers. As the ice melts, they fill up with water and turn into lovely alpine lakes. The glacier's material, such as large and small rocks, sand, and silt, is deposited. Glacial moraines are formed by these sediments. Here on Vedantu, you will find all the solved answers which will be helpful to you in your exam time and all the resources are available free of cost.
5. Give reasons for the following according to Chapter 3 - Our Changing Earth of Class 7 Social Science Our Environment.
Some rocks have the shape of a mushroom.
Flood plains are very fertile.
Sea caves are turned into stacks.
Buddings collapse due to earthquakes.
1. Because of the following factors, some rocks have the shape of a mushroom:
When rocks fall during a dust storm, the suspended sand particles strike the lowest portions of the rocks and erode them.The higher portions of the rocks have not been harmed or eroded. The rocks eventually take on the shape of a mushroom.
2. Flood plains are extremely fertile because they are made up of silt and other materials carried by floods. The floodplains have become fertile due to the spread of new silt.
3. Because of the following factors, sea caves are transformed into stacks:
Sea waves pound the shores, eroding the fragile rocks. Hard rocks do not erode. Sea caves are formed as a result of this action. The caves' roofs eventually collapse due to erosion, leaving the arms/walls of the caverns standing like pillars. These pillar-like formations are known as stacks.
4. Buildings collapse as a result of earthquakes for a variety of reasons:
The majority of structures are not designed or constructed to withstand earthquakes.
When earthquakes strike, buildings are unable to withstand the vibrations caused by the tremors. They crumble due to a weak base, inferior inner materials, and insufficient steel. They disintegrate and fall apart like a stack of papers or cards.
